The US envoy on North Korean policy has arrived in Japan as part of a tour aimed at cooling tensions on the Korean peninsula.
Stephen Bosworth flew into Tokyo on Thursday, following a trip to China to seek its help in dealing with Pyongyang and discuss attempts to convince the North to end its disputed nuclear programme.
The US has even been trying to persuade China, North Korea's biggest aid supplier, to engage in the negotiations.
Tensions between the two Koreas have been at their highest level in years since four South Koreans, including two civilians, were killed when the North shelled the disputed frontier island of Yeonpyeong in November.
Although North Korea has proposed unconditional negotiations with the South, the US and South Korea say that it must adhere to the 2005 agreement to abandon all nuclear programmes.
On Wednesday, Pyongyang called for "positive dialogue" with Seoul but that has been dismissed by the South as "propaganda".
Al Jazeera's Azhar Sukri reports.
Source: Al Jazeera